I don't know if ths would help, but I cleaned my oven on Mon/Tues with Oven Pride. You take the tray and shelves and pop them in a bag (supplied) and pour on the liquid, then leave them to soak overnight, turning the bag occasionally so all bits get covered. I took mine out yesterday and shed them down and they were gleaming, like new. Might work n BBQ bits and pieces? Read reviews on Amazon, but cheaper to buy in Morrisons at £3.99.

Seriously, I was tagged how good things came out (used it on oven door glass too)

I've got some Oven Pride which I've never tried - if its OK for cast iron maybe I'll try it at the end of the BBQ season (hopefully that's not tomorrow!) so thanks for that thought. But I'm really looking for something to use after each time we use it, don't want to pay the price of the sausages for the cleaner!